This invention relates to electrographic copiers having three or more development stations as used, for example, in color copiers/duplicators.
It is known from commonly assigned U.S. Pat. No. 4,477,176, issued Oct. 16, 1984 in the name of M. J. Russel to provide a color electrographic copier having a plurality of development stations for applying toners of different colors to electrostatic images formed on one side of a photoconductor in the form of a continuous web. As disclosed in that patent, the development stations are located on one side of the web and back-up rollers on the opposite side of the web selectively deflect the web into operative relationship with one or another of the development stations so that an image on the web can be developed with toner from a single station. The back-up rollers can be moved by solenoids, for example. While apparatus of this type may work satisfactorily, the rate of production of completed copy sheets may be slow due, in part, to the need for applying toner from only one station at a time. Thus when three toning stations are to be used to apply toner to three different but related images on a photoconductor it is necessary to allow a relatively long strip of the photoconductor to pass the several development stations while only one toning station is applying toner to an image in order to avoid overlapping of different colored toners onto a single image. Clearly it would be desirable to operate more than one of the development stations to apply toner to two different images on the photoconductor simultaneously in order to increase the throughput or copying rate of the apparatus.